libct/cgroups: move RemovePath from fs2

This is to be used by RemovePaths.

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>

libcontainer/cgroups/fs2/fs2.go

@@ -4,14 +4,12 @@ package fs2
 
 import (
 	"io/ioutil"
-	"os"
 	"path/filepath"
 	"strings"
 
 	"github.com/opencontainers/runc/libcontainer/cgroups"
 	"github.com/opencontainers/runc/libcontainer/configs"
 	"github.com/pkg/errors"
-	"golang.org/x/sys/unix"
 )
 
 type manager struct {
@@ -157,45 +155,8 @@ func (m *manager) Freeze(state configs.FreezerState) error {
 	return nil
 }
 
-func rmdir(path string) error {
-	err := unix.Rmdir(path)
-	if err == nil || err == unix.ENOENT {
-		return nil
-	}
-	return &os.PathError{Op: "rmdir", Path: path, Err: err}
-}
-
-// removeCgroupPath aims to remove cgroup path recursively
-// Because there may be subcgroups in it.
-func removeCgroupPath(path string) error {
-	// try the fast path first
-	if err := rmdir(path); err == nil {
-		return nil
-	}
-
-	infos, err := ioutil.ReadDir(path)
-	if err != nil {
-		if os.IsNotExist(err) {
-			err = nil
-		}
-		return err
-	}
-	for _, info := range infos {
-		if info.IsDir() {
-			// We should remove subcgroups dir first
-			if err = removeCgroupPath(filepath.Join(path, info.Name())); err != nil {
-				break
-			}
-		}
-	}
-	if err == nil {
-		err = rmdir(path)
-	}
-	return err
-}
-
 func (m *manager) Destroy() error {
-	return removeCgroupPath(m.dirPath)
+	return cgroups.RemovePath(m.dirPath)
 }
 
 func (m *manager) Path(_ string) string {

libcontainer/cgroups/utils.go

@@ -207,6 +207,43 @@ func EnterPid(cgroupPaths map[string]string, pid int) error {
 	return nil
 }
 
+func rmdir(path string) error {
+	err := unix.Rmdir(path)
+	if err == nil || err == unix.ENOENT {
+		return nil
+	}
+	return &os.PathError{Op: "rmdir", Path: path, Err: err}
+}
+
+// RemovePath aims to remove cgroup path. It does so recursively,
+// by removing any subdirectories (sub-cgroups) first.
+func RemovePath(path string) error {
+	// try the fast path first
+	if err := rmdir(path); err == nil {
+		return nil
+	}
+
+	infos, err := ioutil.ReadDir(path)
+	if err != nil {
+		if os.IsNotExist(err) {
+			err = nil
+		}
+		return err
+	}
+	for _, info := range infos {
+		if info.IsDir() {
+			// We should remove subcgroups dir first
+			if err = RemovePath(filepath.Join(path, info.Name())); err != nil {
+				break
+			}
+		}
+	}
+	if err == nil {
+		err = rmdir(path)
+	}
+	return err
+}
+
 // RemovePaths iterates over the provided paths removing them.
 // We trying to remove all paths five times with increasing delay between tries.
 // If after all there are not removed cgroups - appropriate error will be